The problem:
I cannot ping the Win2003 Server from Solaris.
From Solaris I can ping router and WinXP.
From WinXP and from Win2003 I can ping all the others.
From Solaris DNS is working, I am browsing the web from Solaris now.

thanks for your quick reply.
I've tried to add that route in Solaris, and it worked, but there is still
no reply trying to ping the server.
Do you think that there is something that must be set on the Solaris side to
let it 'talk' to another subnet, or shall I research more on the VMware
side, how to make virtual networks visible to other machines in the LAN?

Is the VMware instance running with NAT enabled? If so, the VMware
instance likely won't be accessible directly. You could, for example,
try and ssh from the Win2k3 machine to the Solaris machine and see what
IP address you actually end up coming from by using 'who.' I would
suspect that when you did, you'll actually observe that your IP has been
NAT'd to 192.168.1.99.

In VMware, I believe the other networking option would be bridged, where
you'll give the VMware instance a 192.168.1/24 address, instead of doing
NAT. This will give your internal setup a little bit more network
coherency.